So far, it has been proposed that in order to make a wiring harness to be mounted on a motor vehicle light, a material for an element wire of a core wire of an electric wire is changed from copper or copper alloy used in general to aluminum or aluminum alloy (for example, see Patent Publication 1). A terminal fitting is attached to the core wire at an end of the electric wire by caulking, so that the electric wires construct the wiring harness.    Patent Publication 1 Japanese Patent Application Laid-Open No. 2005-50736